V4 Extrusion Machine Products
After quite a bit of travelling I’m finally in Eindhoven at the Precious Plastic HQ. My aim while here is to explore and push the limits of the products emerging from the extrusion machine. As you may have seen from Nate’s topic, the machine is far more beefy than before, so with this new power we’ll be testing out some fresh ideas and see what could be possible in the future.This topic will serve as a platform to share our experiments and document the trails and errors.. if you have any questions or suggestions, shoot ’em this way!
The board is no replacement for traditionally made skateboards, but I think there’s value and potential in the use of plastic.
Test: Using the extrusion machine as an injection machine
Objective: To fill larger moulds with plastic
Mould: CNC Aluminium and wood
Almost as simple as screwing on a mould and pushing Go. The mould we used was a skateboard mould originally designed to the compression moulding process by @jasonknight. In order to use it for injecting we needed to make some slight adaptions. One of the most crucial being a nozzle that can be attached independently of the mould (to avoid having to spin the entire mould into the thread of the extrusion). To do this we used an old flexible female connector taken from an oven (image 1). Knowing that this was a proof of concept, we just clamped the two halves of the mould together with the wood barrier in between.
-Larger cavities/moulds can be filled with a stronger extrusion machine.-Better results were achived in a pre-heated mould.
-The cycle time for large products is fast. We were able to inject a board in 20 mins and begin another 30 mins after.
-Wood could be a suitable mould substitute (needs further testing)
-Huge amounts of pressure can be generated inside the mould, therefore safety mechanisms should be considered and strong fasteners used.
-The actual board is rather thick and heavy, but it is strong enough to skateboard and even holds up to tricks. In future test we will look at what the position of the nozzle does to the strength of the board as well as time.
Our first tests with the beefed up extruder where to see how fast we could fill a large mould.
The mould used was a square tube 120x120x500mm with a wooden plunger (image 1) to create some resistance.
The material was a batch of donated plastic (70% black PP, 30%HDPE). We set the final heater on the nozzle to 180 °C and ran the machine between 300-400 rpm.
On average we were able to fill the mould in 20 minutes with another 20mins of cooldown time. Each solid came out slighty different due to the amount of resistance we applied with the plunger (image 2). With the first block we let the plunger rest freely in the mould, the resulting surface was inconsistent with large cavities within the block. While making the second solid we applied varying amounts of pressure against the plunger. It resulted in a slightly better surface and far less cavities. For the third test we decided to remove the plunger and cap the mould. It gave us a good idea of what the plastic was doing in the mould and provided a timelime of sorts. There was a big pressure build up towards the end which resulted in a very dense block (image 3).
If you created a void in the center, A smaller pipe, inside the larger one, you would have trapped air in each.And use far less plastic to produce.Or a low pressure pipe.Me I wanna build floating greenhouses,
How well do they float?
Hey @btmetz, it seems that its quite hard to avoid the cavities in the beams unless you have a homogeneous mix of plastic type and pressure during the process. We’ve got some sections with no holes but will need some more work figuring out the sweet spots.
As far as extruding different shapes, @cymek and myself will be testing out different nozzles with the new machine and hopefully we’ll find something that can produce large flat surfaces easily.
I hope to build a hexagon shaped pipe with a large round pipe for the void.Then divide the hexagon pipe into slices, an insert clear plastic bottles sections into the holes and connect the hexagon frames into domes.
Due to the speed we were able to push the extruder we did some tests with a longer thinner mould. For these beams we used a length of 75x1440mm round tube as well as a plunger (image 1).
Material: 70% black PP, 30%HDPE.
Machine settings: 300-400 rpm. Nozzle Temp: 180 °C
On average we were able to fill the mould in 15mins with another 20mins of cooldown time. The beams are very strong but the surface varies a lot (image 2). With the first beam the surface was rough to begin with but as the mould warmed up it began to smooth out. The second beam was a test to see what happens with the speed was set slightly slower, the result was not much different. For the third beam we set the speed to about 290rpm, used a warm mould and applied a constant pressure to the plunger. These changes appear to have made the beam (image 3) far more smooth and dense.
Wow looking really cool good job 👏🏼
The only further developments with the board have been in the mould (it’s now completely made from Aluminium and able to be pre-heated) and we’ve tested with PS.
@jasonknight has been working on the mould. We’ve been doing much of the making in house 🙂
Here are some pics
Also where did you guys get the mold? Or did you guys create the mold too?
Have you guys done any further work with the recycled skate board? As in different materials to reduce weight and increase strength? Working on a similar project myself. Any feedback would be much appreciated, thanks for all your contributions!!
number 3 looks promising but still far from a usable salable product here in the Philippines.
One of the uses for the recycled material I am looking at here is as a local made engineering plastic.
The Chinese sellers in downtown Manila used to sell made in China recycled HDPE rod but it had voids and the sellers have switched to Korea and Euro made plastic rods.
If that nut could be cracked It would make a very rewarding niche product.
Secondly, Has anyone here been experimenting with plastic welding the various parts? I have seen the various plastic welders on the market, and not wanting to spend 1500USD I built one for around 200USD. I still have not tested it aside from melting plastics and some other experimentations. However if we had flat boards of HDPE extruded, it could be possible to weld them into a boat. Living in a tropical archipelago I see that there are a lot of small boats needed. Plywood/fiberglass does not last all that long. Roto molding is possible as I have seen many DIY large powder coating ovens locally but for my budget at this time, not practical.
You could then pump water into the frame created by the voids, to get it to rise or sink.For example in bad weather.
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